As the old saying goes, “two heads are better than one,” and the same can be said about propulsion systems in a vehicle. By combining an internal combustion engine and an electric motor that uses energy stored in a battery, hybrid electric and plug-in hybrid electric vehicles are some of the most efficient vehicles on the market — lowering drivers’ operating costs, increasing energy security and reducing greenhouse gas emissions.

A number of plug-in hybrids and hybrid electrics can be found on FuelEconomy.gov’s Top Ten EPA-Rated Fuel Sippers list, and the Alternative Fuel Data Center’s Vehicle Cost Calculator shows that the average driver would spend half as much money on fuel by driving a plug-in hybrid electric vehicle compared to an equivalent conventional vehicle. In addition to saving drivers money, plug-ins — which can drive from 10 to 40 miles on electric power alone, depending on the model — use domestically produced electricity that supports the U.S. economy. In fact, transitioning America’s vehicle fleet to hybrid and plug-in hybrid vehicles could reduce U.S. foreign oil dependence by nearly 80 percent and greenhouse gas emissions by 60 percent. Recognizing these benefits, the Energy Department funds research on technologies that can make both hybrid electric and plug-in hybrid electric vehicles cheaper and more efficient.

With help from the Clean Cities National Parks Initiative, Grand Teton National Park was able to purchase hybrid electric vehicles, which the park’s Wildlife Brigade use to spark discussions about emission and fuel efficiency. image via National Park Service

While hybrid electrics and plug-in hybrid electrics use many of the same technologies as conventional vehicles, they also require some specialized ones, including batteries, power electronics and electric motors. In hybrid and plug-in hybrid vehicles, batteries must be larger to store more energy and help propel the vehicle. The Department has robust research and development programs to investigate new, advanced chemistries and components for batteries in which we are working to develop battery technologies that provide more power and storage at a lower cost than today’s nickel-metal-hydride and lithium-ion. Through the U.S. Advanced Battery Consortium, the Department collaborates with industry on applied research to integrate batteries into full energy storage systems for vehicles, test technologies before they enter the market, and benchmark existing batteries for comparison against future improvements. In the last four years, our work has helped cut the cost of lithium-ion batteries for plug-in hybrid electric vehicles in half.

Power electronics and electric motors primarily work to convert energy stored in the battery into energy that is used to turn a vehicle’s wheels. The Department’s research in these areas focus on improving power management and increasing heat removal from power electronics systems to lower cost, increase reliability and decrease weight. It also researches new types of electric motors, including those that do not rely on expensive and imported rare earth materials.

In addition to research, the Department has supported manufacturing of vehicle batteries and components that are used in electric drive through the American Recovery and Reinvestment Act. While the U.S. previously produced very few advanced automotive batteries, our $2 billion investment has set a foundation for an advanced vehicle industry in the United States. One of these competitively awarded projects is Magna E-Car Systems of America, Inc.

With a $40 million award from the Department and $47.4 million investment from the company, Magna opened a new facility located in Grand Blanc Township, Michigan, in April. The 66,000-square-foot facility manufactures electric drive components, including electric motors, inverters and electronic powertrain controllers for the Ford Focus EV, and can also supply components to companies producing hybrids and plug-in hybrids. At full capacity, the facility can support 100,000 all-electric vehicles.

Hybrids and plug-in hybrids offer great potential for reducing our dependence on imported oil and saving drivers money on fuel, and are also helping automakers meet the 54.5 miles per gallon fuel economy and emissions standards by 2025.

How Do Hybrids Differ?

Hybrid electric vehicles use regenerative braking (when the vehicle captures energy that would be otherwise lost from braking) and the engine charge the battery, which can provide extra power to their internal combustion engines and run auxiliary systems like headlights and dashboards.

In plug-in hybrid electric vehicles, drivers recharge the battery by plugging it into the electric grid, although it can also receive some charge from regenerative braking.

The mission of the Energy Department is to ensure America’s security and prosperity by addressing its energy, environmental and nuclear challenges through transformative science and technology solutions